All Magnum heads are functionally the same. The 5.2 Mags are US sourced, the 5.9 heads are Mexico, although there has never been a preference one to the other.

There is some confusion about the name R/T. At the same time that Mopar was selling a model with the R/T name, they were selling Magnum R/T heads. The two are not the same. The heads in the R/T trucks were exactly the same as any other Mag head. The MP Magnum R/T heads were better flowing and if MP ran true to form back then, they were pretty expensive. I don't think you can get them new any more and cost is probably the reason.

The Mag heads had the best combustion chamber of any OEM Mopar up until that time. Dual squish pads really can wake up the air/fuel if the engine is built for squish. The intake side flowed adequately and the exhaust was relatively high flowing. Mag heads do not usually need a dual pattern cam.

IF you are looking for better heads the first that come to mind are Enginequest. These cast iron heads aren't cheap, but they are capable of making more power, just out of the box. Then there are the Edelbrock Mag heads and now the Sidewinder smallblock may have provisions for Mag stuff, call Mr. Marsh (Sasquatch). Speedmaster (ProComp) has a cast iron head that is Mag configuration. There may be others but that's all that come to mind.

R.